This invention relates to the controlling of the operation of a plurality of electric motors and more specifically to controlling the operation of a plurality of electric motors used in association with a vehicle transmission.
A known shifting mechanism for use in association with a vehicle transmission is disclosed in U.S. Pat. No. 4,873,881 issued Oct. 17, 1989 and entitled "Electrically Actuated X-Y Shifting Mechanism". This shifting mechanism is easily connectable to and is compatible with shift bar housing assemblies of normally manually actuated mechanical transmissions without modification thereto. The shift mechanism provides for automatic or semi-automatic shifting of the otherwise substantially standard, normally manually shifted, transmission. This known shifting mechanism includes a rail select electric motor which is used to select a desired shift rail and an in-gear electric motor which is utilized to effect movement of the shift rail to engage or disengage a jaw clutch associated with the selected shift rail.
The electrical circuitry for controlling the operation of the rail select and the in-gear electric motors has previously included control circuitry having four switches for each electric motor. Two of the control switches associated with an electric motor are used to effect forward operation of the electric motor. The other two switches associated with the electric motor are used to effect reverse operation of the motor. Switches used to control the operation of either motor must be capable of conducting relatively large currents required to energize the motor. The cost of the motor control circuitry can be reduced by reducing the number of switches used to control the operation of the motors.